1. Field of the Invention
This invention relates to undenatured virus-free biologically active protein-containing compositions. More especially, this invention relates to the inactivation of viruses, especially lipid coated viruses, e.g., hepatitis B in human blood, blood component, blood plasma or any fraction, concentrate or derivative thereof containing blood proteins non-blood sources including normal or cancer cells, the exudate from cancer or normal cells grown in culture, hybridomas, in products from gene splicing (DNA), etc., by use of di- or trialkyl phosphates, and to the resultant products. In particular, this invention relates to blood plasma or other plasma protein-containing compositions which are to be rendered substantially free of hepatitis B and/or non-A and non-B hepatitis or other viral infectivity, such blood plasma or fractions thereof having valuable labile proteins, such as, for example, factor VIII.
2. Discussion of Prior Art
Numerous attempts have been made to inactivate viruses such as hepatitis B virus (HBV) in mammalian, especially human, blood plasma. It is the practice in some countries to effect inactivation of the hepatitis B virus in the blood plasma by contacting the plasma with a viral inactivating agent of the type which crosslinks with the proteinaceous portion of hepatitis B virus, or which interacts with the nucleic acid of the virus. For instance, it is to attempt to inactivate hepatitis B virus by contact an aldehyde such as formaldehyde whereby crosslinking to the protein is effected and the hepatitis B virus is inactivated. It is also known to effect inactivation of the virus by contact with beta-propiolactone (BPL), an agent which acts on the nucleic acid of the virus. It is further known to use ultraviolet (UV) light, especially after a beta-propiolactone treatment.
Unfortunately, these agents often alter, denature or destroy valuable protein components especially so-called "labile" blood coagulation factors of the plasma under conditions required for effective inactivation of virus infectivity. For instance, in such inactivation procedures, factor VIII is inactivated or denatured to the extent of 50-90% or more of the factor VIII present in the untreated plasma. Because of the denaturing effects of these virus inactivating agents, it is necessary in the preparation of derivatives for administration to patients to concentrate large quantities of plasma so that the material to be administered to the patient once again has a sufficient concentration of the undenatured protein for effective therapeutic treatment. This concentration, however, does not affect reduction of the amount of denatured protein. As a result, the patient not only receives the undenatured protein but a quantity of denatured protein often many times that of the undenatured protein.
For instance, in the inactivation of hepatitis B virus in human blood plasma by beta-propiolactone, there is obtained as a result thereof, a plasma whose factor VIII has been 75% inactivated. The remaining 25% of the factor VIII is therefore present in such a small concentration, as a function of the plasma itself, that it is necessary to concentrate large quantities of the factor VIII to provide sufficient concentration to be of therapeutic value. Since such separation techniques do not efficiently remove denatured factor VIII from undenatured factor VIII, the material administered to the patent may contain more denatured protein than undenatured protein. Obviously, such inactivation is valuable from a standpoint of diminishing the risk of hepatitis virus infection. However, it requires the processing of large quantities of plasma and represents significant loss of valuable protein components. Furthermore, administration of large amounts of denatured proteins may render these antigenic to the host and thus give rise to autoimmune diseases, or perhaps, rheumatoid arthritis.
The loss of these valuable protein components is not limited to factor VIII, one of the most labile of the valuable proteins in mammalian blood plasma. Similar protein denaturation is experienced in respect of the following other valuable plasma components: coagulation factors II, VII, IX, X; plasmin, fibrinogen (factor I) IgM, hemoglobin, interferon, etc.
Factor VIII, however, is denatured to a larger extent than many of the other valuable proteins present in blood plasma.
As a result of the foregoing, except in the processing of serum albumin, a stable plasma protein solution which can withstand pasteurization, it is largely the practice in the United States in respect of the processing of blood proteins to take no step in respect of the sterilization for inactivation of viruses. As a result, recipients of factor VIII, gamma-globulin, factor IX, fibrinogen, etc., must accept the risk that the valuable protein components being administered may be contaminated with hepatitis viruses as well as other infectious viruses. As a result, these recipients face the danger of becoming infected by these viruses and having to endure the damage which the virus causes to the liver and other organ systems and consequent incapacitation and illness which may lead to death.
The BPL/UV inactivation procedure discussed above has not so far been adopted in the United States for numerous reasons, one of which lies in the fact that many researchers believe that BPL is itself deleterious since it cannot be removed completely following the inactivation and thus may remain in plasma and plasma derivatives. BPL has been shown to be carcinogenic in animals and is dangerous even to personnel handling it.
Other methods for the inactivation of hepatitis B virus in the plasma are known, but are usually impractical. One method involves the addition of antibodies to the plasma whereby an immune complex is formed. The expense of antibody formation and purification add significantly to the cost of the plasma production; furthermore, there is no assurance that a sufficient quantity of hepatitis B or non-A, non-B virus is inactivated. There is currently no test for non-A, non-B antibodies (although there is a test for the virus); hence, it is not possible to select plasma containing high titers of anti non-A, non-B antibody.
It is to be understood that the problems of inactivation of the viruses in plasma are distinct from the problems of inactivation of the viruses themselves due to the copresence of the desirable proteinaceous components of the plasma. Thus, while it is known how to inactivate the hepatitis B virus, crosslinking agents, for example, glutaraldehyde, nucleic acid reacting chemicals, for example BPL or formaldehyde, or oxidizing agents, for example chlorox, etc., it has been believed that these methods are not suitable for the inactivation of the virus in plasma due to the observation that most of these activating agents (sodium hypochlorite, formaldehyde, beta-propiolactone) denatured the valuable proteinaceous components of the plasma.
U.S. Pat. No. 4,315,919 to Shanbrom describes a method of depyrogenating a proteinaceous biological or pharmaceutical product by contacting such proteinaceous product with a non-denaturing amphiphile.
U.S. Pat. No. 4,314,997 to Shanbrom describes a method of reducing pyrogenicity, hepatitis infectivity and clotting activation of a plasma protein product by contacting the product with a non-denatured amphiphile.
Both Shanbrom '919 and '997 contemplate the use of a non-ionic detergent, for example, "Tween 80" as the amphiphile. It will be shown hereinafter that treatment with "Tween 80" by itself is relatively ineffective as a viral inactivating agent.
U.S. Pat. No. 3,962,421 describes a method for the disruption of infectious lipid-containing viruses for preparing sub-unit vaccines by contacting the virus in an aqueous medium with a wetting agent and a trialkylphosphate. Such aqueous medium is defined as allantonic fluid, tissue culture fluid, aqueous extract or suspension of central nervous system tissue, blood cell eluate and an aqueous extract or suspension of fowl embryo. The patent does not describe hepatitis, nor is it concerned with preparation of blood derivatives containing labile blood protein substantially free of viral infectivity. It is only concerned with disrupting the envelope of lipid containing viruses for the production of vaccines and not with avoiding or reducing protein denaturation en route to a blood derivative.
Problems may also exist in deriving valuable proteins from non-blood sources. These sources include, but are not limited to, mammalian milk, ascitic fluid, saliva, placental extracts, tissue culture cell lines and their extracts including transformed cells, and products of fermentation. For instance, the human lymphoblastoid cells have been isolated which produce alpha interferon. However, the cell line in commercial use today contains Epstein-Barr virus genes. It has been a major concern that the use of interferon produced by these cells would transmit viral infection or induce viral caused cancerous growth.
The present invention is directed to achieving three goals, namely, (1) a safe, (2) viral inactivated protein-containing composition, (3) without incurring substantial protein denaturation. As shown above these three goals are not necessarily compatible since, for example beta-propiolactone inactivates viral infectivity, but is unsafe and substances such as formaldehyde inactivate viruses, but also substantially denaturate the valuable plasma proteins, for example, factor VIII.
It, therefore, became desirable to provide a process for obtaining protein-containing compositions which does not substantially denature the valuable protein components therein and which does not entail the use of a proven carcinogenic agent. More especially, it is desirable to provide blood protein-containing compositions in which substantially all of the hepatitis viruses and other viruses present are inactivated and in which denatured protein such as factor VIII account for only a small amount of the total amount of these proteins in the blood protein-containing composition.
It is a further object to provide products from cancer or normal cells or from fermentation processes following gene insertion which are substantially free of virus, especially lipid-containing viruses.